1. Field of the Invention
The invention relates to a secondary battery in which interface resistance is decreased.
2. Description of Related Art
With the rapid spread in recent years of information-related equipment, communication equipment, and the like, such as personal computers, video cameras and mobile phones, emphasis is placed on the development of batteries used as power sources therefor. In addition, development of high output and high capacity battery for electric vehicles or for hybrid vehicles is also moving forward in the world of automotive industry, or the like. Currently, among a variety of batteries, lithium secondary batteries are drawing attention from the point of view of high energy density.
In the field of such lithium secondary batteries, a variety of studies are being conducted in order to reduce the interface resistance between active materials and electrolytes. For instance, an all-solid-state lithium secondary battery is described in Japanese Patent Application Publication No. 2009-193803 (JP-A-2009-193803), having, between a negative electrode layer and a sulfidic solid electrolyte layer, a Li ion conductor-modification layer that is electrochemically stable and has no electron conductivity, against the negative electrode layer. This is intended to improve the output by suppressing the formation of a space-charge layer at the interface on the negative electrode layer side of the sulfidic solid electrolyte layer thereby decreasing resistance against lithium ion conduction.
In addition, Japanese Patent Application Publication No. 2002-042862 (JP-A-2002-042862) describes a lithium battery that is impregnated between active material particles and oxidic inorganic solid electrolyte particles with sulfolane, which is a solvent having high permittivity and excellent ion conductivity, or at least one among derivatives thereof. Further, Japanese Patent Application Publication No. 2007-005279 (JP-A-2007-005279) describes a layered body for an all-solid-state lithium secondary battery containing an active material layer and a solid electrolyte layer joined to the active material layer by sintering, the layered body having no component other than the constituents of the active material layer and the constituents of the solid electrolyte layer detected when analyzed by the X-ray diffraction method, as well as an all-solid-state lithium secondary battery using such a layered body.
In the secondary batteries of the related arts described above, as the interface resistance between the electrode active material and the electrolyte material is large, the capacity sometimes drops noticeably charged-discharged at high rates.